PD Dr. M. Johannsen

The recovery of high purity products from natural sources has gained more and more interest. In order to obtain pure substances from natural sources at process-scale, adsorptive separation provides a possible process. Thereby single stage adsorption / desorption as well as multistage adsorption processes such as chromatography can be applied. The knowledge of adsorption equilibrium is of fundamental importance for the design of every adsorption processes. Due to the complex nature of adsorbent-adsorbate interactions, prediction of the required phase equilibria especially of multicomponent systems from sub- and supercritical solutions is mostly insufficient, up to now. Therefore, on one hand fast and reliable methods for experimental determination of adsorption equilibria are needed, and on the other hand generation of a broad experimental data basis for different systems is necessary.

The apparatus for experimental determination of adsorption equilibria present at the Institute of Thermal and Separation Processes allows measurements by injecting samples as a finite slug (perturbation method, ECP method) as well as continuous feeding of sample solution (frontal analysis).

Fig. 1: Apparatus for adsorption measurement, Fig. 2: Mixture isotherms of α-Tocopherol(p=20 MPa, T=313 K, α/δ-Toco)

The objective of this project is the determination of adsorption of low volatile compounds (different selected natural substances) from sub- or supercritical solutions taking into consideration type and composition of desorbent and adsorbent. Additionally, solubilities of low volatile compounds in the desorbent are measured. One important goal of this study is to get new expertise on adsorption phenomena, which will allow the modeling and prediction of adsorption equilibria without or with a few experimental data only.